This invention relates in general to bearings and more particularly to a multirow bearing containing tapered rollers.
The rolling mills in which plates, strips, and other shapes are reduced in thickness contain opposed work rolls between which the steel shape passes, and often back-up rolls which bear against the surfaces of the work rolls to rigidify them so that they do not spread apart to any significant extent as the shape passes between them. The ends of the work and back-up rolls are reduced in diameter to provide so-called roll necks, and these roll necks are received in bearings which in turn are mounted in housings called chocks. Since the spreading and other deflecting forces on the work rolls are of substantial magnitude, the back-up rolls must be capable of sustaining high radial loads and must otherwise be of a highly durable construction. Frequently, they are tapered roller bearings having their tapered rollers arranged in four rows with the large diameter ends of the rollers in two of the rows facing in one axial direction and the large diameter ends of the rollers in the other two rows facing in the opposite axial direction. Various arrangements of these rows are possible.
To facilitate removal of the bearings from the roll necks, a loose fit is usually provided between the inner races of a bearing and the roll neck around which it fits, and this enables contaminants to migrate along the roll neck and enter the interior of the bearing at the abutment between the two double cones that constitute the inner race.
Not only does the plate, strip, or other shape that is being rolled tend to spread the rollers apart, but it also tends to deflect the work rolls in the horizontal direction, this being due to differential strip tensions or work roll offset. The work roll chocks, however, fix the bearings firmly in place and consequently as to each bearing the rollers of the two rows closest to the working surfaces of the roll take a higher radial load than the rollers of the two outer rows, although this increased load is not shared evenly between those rollers.
Aside from the foregoing, the seals that protect conventional roll neck bearing arrangements are remote from the bearings and are often damaged when the roll is removed for regrinding and thereafter replaced, which occurs frequently insofar as the work rolls are concerned. For example, the innermost seal of at least one of the bearings is sometimes inverted when the roll is replaced and the bearings are installed around its necks. An inverted seal, of course, allows contaminants to enter the interior of the bearing where they have a deleterious effect.